feat: retire C-list entries for resolved promises

packages/SwingSet/src/kernel/cleanup.js

@@ -1,4 +1,4 @@
-import { kdebug } from './kdebug';
+// import { kdebug } from './kdebug';
 import { parseKernelSlot } from './parseKernelSlots';
 
 // XXX temporary flags to control features during development
@@ -18,45 +18,94 @@ export function deleteCListEntryIfEasy(
 
     function scanKernelPromise(scanKPID, scanKernelData) {
       visited.add(scanKPID);
-      kdebug(`@@@ scan ${scanKPID}`);
+      // kdebug(`@@@ scan ${scanKPID} ${JSON.stringify(scanKernelData)}`);
       if (scanKernelData) {
         for (const slot of scanKernelData.slots) {
           const { type } = parseKernelSlot(slot);
           if (type === 'promise') {
             sawPromise = slot;
             if (visited.has(slot)) {
-              kdebug(`@@@ ${slot} previously visited`);
+              // kdebug(`@@@ ${slot} previously visited`);
               return true;
             } else {
-              const { data, state } = kernelKeeper.getKernelPromise(slot);
+              const { data } = kernelKeeper.getKernelPromise(slot);
+              // const { data, state } = kernelKeeper.getKernelPromise(slot);
               if (data) {
                 if (scanKernelPromise(slot, data)) {
-                  kdebug(`@@@ scan ${slot} detects circularity`);
+                  // kdebug(`@@@ scan ${slot} detects circularity`);
                   return true;
                 }
               } else {
-                kdebug(`@@@ scan ${slot} state = ${state}`);
+                // kdebug(`@@@ scan ${slot} state = ${state}`);
               }
             }
           }
         }
       }
-      kdebug(`@@@ scan ${scanKPID} detects no circularity`);
+      // kdebug(`@@@ scan ${scanKPID} detects no circularity`);
       return false;
     }
 
-    kdebug(`@@ checking ${vatID} ${kpid} for circularity`);
+    // kdebug(`@@ checking ${vatID} ${kpid} for circularity`);
     if (scanKernelPromise(kpid, kernelData)) {
-      kdebug(
-        `Unable to delete ${vatID} clist entry ${kpid}<=>${vpid} because it is indirectly self-referential`,
-      );
+      // kdebug(
+      //  `Unable to delete ${vatID} clist entry ${kpid}<=>${vpid} because it is indirectly self-referential`,
+      // );
       return;
     } else if (sawPromise) {
-      kdebug(
-        `Unable to delete ${vatID} clist entry ${kpid}<=>${vpid} because there was a contained promise ${sawPromise}`,
-      );
+      // kdebug(
+      //  `Unable to delete ${vatID} clist entry ${kpid}<=>${vpid} because there was a contained promise ${sawPromise}`,
+      // );
       return;
     }
   }
   vatKeeper.deleteCListEntry(kpid, vpid);
 }
+
+export function getKpidsToRetire(
+  vatID,
+  vatKeeper,
+  kernelKeeper,
+  rootKPID,
+  rootKernelData,
+) {
+  const seen = new Set();
+  function scanKernelPromise(kpid, kernelData) {
+    // kdebug(`### scanning ${kpid} ${JSON.stringify(kernelData)}`);
+    if (vatKeeper.hasCListEntry(kpid)) {
+      // kdebug(`## adding ${kpid} to scan results`);
+      seen.add(kpid);
+      if (kernelData) {
+        for (const slot of kernelData.slots) {
+          const { type } = parseKernelSlot(slot);
+          // kdebug(`## examine ${kpid} slot ${slot}`);
+          if (type === 'promise') {
+            if (!seen.has(slot)) {
+              const kp = kernelKeeper.getKernelPromise(slot);
+              const { data, state } = kp;
+              // kdebug(`## state of ${slot} is: ${JSON.stringify(kp)}`);
+              if (state !== 'unresolved') {
+                if (data) {
+                  scanKernelPromise(slot, data);
+                }
+              } else {
+                // kdebug(`## ${slot} is still unresolved`);
+              }
+            } else {
+              // kdebug(`## ${slot} previously seen`);
+            }
+          } else {
+            // kdebug(`## ${slot} is not a promise`);
+          }
+        }
+      } else {
+        // kdebug(`## ${kpid} has no data`);
+      }
+    } else {
+      // kdebug(`## ${kpid} has no c-list entry for ${vatID}`);
+    }
+  }
+
+  scanKernelPromise(rootKPID, rootKernelData);
+  return Array.from(seen);
+}

packages/SwingSet/src/kernel/kernel.js

@@ -472,7 +472,16 @@ export default function buildKernel(
       kernelKeeper.incStat(statNameForNotify(p.state));
       const kd = harden(['notify', kpid, p]);
       const vd = vat.translators.kernelDeliveryToVatDelivery(kd);
-      await deliverAndLogToVat(vatID, kd, vd);
+      if (vd) {
+        await deliverAndLogToVat(vatID, kd, vd);
+
+        const resolutions = vd[1];
+        const vatKeeper = kernelKeeper.getVatKeeper(vatID);
+        for (const vpid of Object.keys(resolutions)) {
+          const kpidToDelete = vatKeeper.mapVatSlotToKernelSlot(vpid);
+          vatKeeper.deleteCListEntry(kpidToDelete, vpid);
+        }
+      }
     }
   }
 

packages/SwingSet/src/kernel/liveSlots.js

@@ -509,30 +509,33 @@ function build(syscall, forVatID, cacheSize, vatPowers, vatParameters) {
     };
   }
 
-  function notify(primaryPromiseID, resolutions) {
+  function notifyOnePromise(promiseID, rejected, data) {
+    insistCapData(data);
+    lsdebug(
+      `ls.dispatch.notify(${promiseID}, ${rejected}, ${data.body}, [${data.slots}])`,
+    );
+    insistVatType('promise', promiseID);
+    // TODO: insist that we do not have decider authority for promiseID
+    if (!importedPromisesByPromiseID.has(promiseID)) {
+      throw new Error(`unknown promiseID '${promiseID}'`);
+    }
+    const pRec = importedPromisesByPromiseID.get(promiseID);
+    const val = m.unserialize(data);
+    if (rejected) {
+      pRec.reject(val);
+    } else {
+      pRec.resolve(val);
+    }
+  }
+
+  function notify(resolutions) {
     assert(didRoot);
     for (const vpid of Object.keys(resolutions)) {
       const vp = resolutions[vpid];
-      insistCapData(vp.data);
-      lsdebug(
-        `ls.dispatch.notify(${primaryPromiseID} ${vpid}, ${vp.rejected}, ${vp.data.body}, [${vp.data.slots}])`,
-      );
-      insistVatType('promise', vpid);
-      // TODO: insist that we do not have decider authority for promiseID
-      if (!importedPromisesByPromiseID.has(vpid)) {
-        throw new Error(`unknown promiseID '${vpid}'`);
-      }
-      const pRec = importedPromisesByPromiseID.get(vpid);
-      const val = m.unserialize(vp.data);
-      if (vp.rejected) {
-        pRec.reject(val);
-      } else {
-        pRec.resolve(val);
-      }
+      notifyOnePromise(vpid, vp.rejected, vp.data);
     }
     for (const vpid of Object.keys(resolutions)) {
-      const vp = resolutions[vpid];
-      retirePromiseIDIfEasy(vpid, vp.data);
+      retirePromiseID(vpid);
     }
   }
 

packages/SwingSet/src/kernel/state/vatKeeper.js

@@ -179,6 +179,17 @@ export function makeVatKeeper(
     return storage.get(kernelKey);
   }
 
+  /**
+   * Test if there's a c-list entry for some slot.
+   *
+   * @param {string} slot  The slot of interest
+   *
+   * @returns {boolean} true iff this vat has a c-list entry mapping for `slot`.
+   */
+  function hasCListEntry(slot) {
+    return storage.has(`${vatID}.c.${slot}`);
+  }
+
   /**
    * Remove an entry from the vat's c-list.
    *
@@ -271,6 +282,7 @@ export function makeVatKeeper(
     getSourceAndOptions,
     mapVatSlotToKernelSlot,
     mapKernelSlotToVatSlot,
+    hasCListEntry,
     deleteCListEntry,
     getTranscript,
     addToTranscript,

packages/SwingSet/src/kernel/vatManager/deliver.js

@@ -81,9 +81,9 @@ export function makeDeliver(tools, dispatch) {
     );
   }
 
-  async function deliverOneNotification(primaryVpid, resolutions) {
-    const errmsg = `vat[${vatID}].promise[${primaryVpid}] failed`;
-    return doProcess(['notify', primaryVpid, resolutions], errmsg);
+  async function deliverOneNotification(resolutions) {
+    const errmsg = `vat[${vatID}].notify failed`;
+    return doProcess(['notify', resolutions], errmsg);
   }
 
   // vatDeliverObject is:

packages/SwingSet/src/kernel/vatManager/nodeWorkerSupervisor.js

@@ -59,9 +59,9 @@ function doMessage(targetSlot, msg) {
   );
 }
 
-function doNotify(primaryVpid, resolutions) {
-  const errmsg = `vat.promise[${primaryVpid}] failed`;
-  return doProcess(['notify', primaryVpid, resolutions], errmsg);
+function doNotify(resolutions) {
+  const errmsg = `vat.notify failed`;
+  return doProcess(['notify', resolutions], errmsg);
 }
 
 parentPort.on('message', ([type, ...margs]) => {

packages/SwingSet/src/kernel/vatManager/subprocessSupervisor.js

@@ -59,9 +59,9 @@ function doMessage(targetSlot, msg) {
   );
 }
 
-function doNotify(primaryVpid, resolutions) {
-  const errmsg = `vat.promise[${primaryVpid}] failed`;
-  return doProcess(['notify', primaryVpid, resolutions], errmsg);
+function doNotify(resolutions) {
+  const errmsg = `vat.notify failed`;
+  return doProcess(['notify', resolutions], errmsg);
 }
 
 const toParent = arrayEncoderStream();

packages/SwingSet/src/kernel/vatTranslator.js

@@ -4,7 +4,7 @@ import { insistKernelType, parseKernelSlot } from './parseKernelSlots';
 import { insistVatType, parseVatSlot } from '../parseVatSlots';
 import { insistCapData } from '../capdata';
 import { kdebug, legibilizeMessageArgs, legibilizeValue } from './kdebug';
-import { deleteCListEntryIfEasy } from './cleanup';
+import { deleteCListEntryIfEasy, getKpidsToRetire } from './cleanup';
 
 /*
  * Return a function that converts KernelDelivery objects into VatDelivery
@@ -79,12 +79,27 @@ function makeTranslateKernelDeliveryToVatDelivery(vatID, kernelKeeper) {
 
   function translateNotify(kpid, kp) {
     assert(kp.state !== 'unresolved', details`spurious notification ${kpid}`);
-    const vpid = mapKernelSlotToVatSlot(kpid);
     const resolutions = {};
-    resolutions[vpid] = translatePromiseDescriptor(kp);
-    deleteCListEntryIfEasy(vatID, vatKeeper, kernelKeeper, kpid, vpid, kp.data);
-    const vatDelivery = harden(['notify', vpid, resolutions]);
-    return vatDelivery;
+    kdebug(`notify ${kpid} ${JSON.stringify(kp)}`);
+    const targets = getKpidsToRetire(
+      vatID,
+      vatKeeper,
+      kernelKeeper,
+      kpid,
+      kp.data,
+    );
+    if (targets.length > 0) {
+      for (const toResolve of targets) {
+        const p = kernelKeeper.getKernelPromise(toResolve);
+        const vpid = mapKernelSlotToVatSlot(toResolve);
+        resolutions[vpid] = translatePromiseDescriptor(p);
+      }
+      const vatDelivery = harden(['notify', resolutions]);
+      return vatDelivery;
+    } else {
+      kdebug(`skipping notify of ${kpid} because it's already been done`);
+      return null;
+    }
   }
 
   function kernelDeliveryToVatDelivery(kd) {
@@ -97,7 +112,7 @@ function makeTranslateKernelDeliveryToVatDelivery(vatID, kernelKeeper) {
       default:
         throw Error(`unknown kernelDelivery.type ${type}`);
     }
-    // returns ['message', target, msg] or ['notify', vpid, vp]
+    // returns ['message', target, msg] or ['notify', resolutions] or null
   }
 
   return kernelDeliveryToVatDelivery;